Exposure apparatus

ABSTRACT

An exposure apparatus and methods for making and using the same. The exposure apparatus includes at least one projection optical system which projects illuminating light, a substrate stage which supports a substrate to be exposed by the illuminating light and which includes a first plurality of reference marks. The exposure apparatus also includes a mask stage which supports a mask that includes a mask pattern to be projected onto the substrate by at least one projection optical system. The mask further includes a second plurality of reference marks intended to correspond to the first plurality of reference marks. The second plurality of reference marks is integrally formed with the mask pattern. The projection optical system(s) project illuminating light based on the mask pattern and the second plurality of reference marks to produce a projected image corresponding to the mask pattern and a plurality of projected images corresponding to the second plurality of reference marks. The exposure apparatus also includes an adjustment mechanism which adjusts the position of the projected image on the substrate based on a plurality of positional relationships between the plurality of projected images and the first plurality of reference marks. Also included is a plurality of sensors which detect the positional relationships, and a control device which controls the adjustment mechanism based on the positional relationships to effect a predetermined plurality of positional relationships between the plurality of projected images and the first plurality of reference marks.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to industrial image exposure devices thatare used in lithographic processes to expose images onto substrates suchas during the manufacture of liquid crystal display panels,semiconductor elements, etc.

2. Description of the Related Art

Industrial imaging devices such as image exposure devices are used toproduce liquid crystal display panels, semiconductor elements, etc. Forexample, personal computers, laptop computers, word processors,televisions, and many other common devices include components that aremanufactured, in part, by using image exposure devices. The manufactureof liquid crystal display panels, for example, has become increasinglyreliant on image exposure devices and techniques. And, as such displaypanels have become more complex and intricate, so too have themanufacturing devices and processes associated with production of thesame.

Liquid crystal display (LCD) panels often are produced, in part, byforming a conductive thin film electrode (e.g., of the Indium Tin Oxide(ITO) variety, etc.) on and affixing a liquid crystal molecularorientation element to a glass substrate and sealing that arrangementwith a sealant or sealing member at the outer periphery of thesubstrate. Formation of ITO-type thin film electrodes and, inparticular, complex LCD display segments have been achieved by imagingthe same via lithographic image exposure devices and processes.

To perform such lithographic processes, a photolithographic imageexposure device known as a “stepper” often is used. With a stepper, adesired pattern contained in a mask or on a reticle may be projectedonto a substrate via a “step and repeat” exposure method. Depending onthe nature of the pattern to be exposed (e.g., the number and complexityof the display units to be exposed, etc.), other patterning devices andtechniques have been used (e.g., scanning exposure devices using mirrorprojection aligners and systems, etc.).

Despite their widespread use to produce LCDs, etc., stepper throughputefficiency has become problematic. That is, as LCD elements haveincreased in complexity, the number of devices that can be made via stepand repeat techniques has decreased. And, when using mirror projectiontype systems, etc., problems also have been realized in terms ofmanufacturing relatively large mirrors and assemblies to expose enlargedmasks. As such, mirror-type systems have resulted in relatively largescanning devices and stepper units.

To address efficiency and size problems associated with prior stepperunits, some have proposed scanning type exposure devices for relativelylarge circuit pattern masks. One such device is disclosed in JapaneseLaid-Open Patent Publication Hei 7-57986 (U.S. Pat. No. 5,729,331). Sucha scanning type exposure device uses plural projection optical systemsto simultaneously scan a mask and a photosensitive substrate. As such,scanning type exposure devices of the type disclosed in theaforementioned Japanese patent publication have led to increased devicethroughput efficiency and decreased stepper size.

An exemplary scanning type exposure device (of the type illustrated inthe aforementioned Japanese patent publication) is shown in drawingfigure (FIG.) 1, which is attached to this document. In particular, thestepper unit exposure device shown in FIG. 1 includes a mask table 122and a plate table 123 which are supported on a carriage 112. Thecarriage has a U-shaped cross-section. The mask and plate tables aresupported opposite each other. A mask 113 and a plate 114 arerespectively supported on tables 122 and 123. A mask-side reference markplate 130 is fixed to the end of the mask table 122, and a plate-sidereference mark plate 128 is fixed opposite to the mask-side referencemark plate 130. Movement of the carriage 112 in the direction of arrowA, causes mask 113 and plate 114 to be scanned by an illuminating system117 and a projection optical system 118. A pattern is formed throughmask 113 via illuminating light from illuminating system 117. To exposeplate 114, the light that passes through mask 113 and which passesthrough projection optical system 118 becomes incident on plate 114. InFIG. 1, actuators 124 a-124 c control the position of the mask tableduring mask setup processes to ensure proper exposure.

The exposure device depicted in FIG. 1 is further illustrated in anddiscussed with regard to FIG. 2 which also is attached hereto. Inparticular, the projection optical system shown in FIG. 1 is made up ofseven optical modules 125 ₁-125 ₇. Each optical module 125 has atrapezoidal exposure field that divides the pattern on mask 113 to becopied/projected onto plate 114. Each optical module 125 has a mechanism126 to adjust the position of the projected image. The trapezoidalregions PA₁-PA₄ are projected by optical modules 125 ₁-125 ₄ whiletrapezoidal regions PA₅-PA₇ are projected by optical modules 125 ₅-125₇.

The trapezoidal regions are aligned in a direction (non-scanningdirection) perpendicular to the scanning direction at a predeterminedspacing. The ends (those portions shown by dashed lines in FIG. 3, whichis attached hereto) of adjacent trapezoidal regions (for example, PA₁and PA₅, PA₅ and PA₂, etc.), and the optical modules 125 ₁-125 ₇ arearranged such that they overlap by a predetermined amount in anon-scanning direction.

In mask-side reference mark plate 130, and in plate-side reference markplate 128, as shown in FIG. 3, mask-side reference marks M₁-M₈, andplate-side reference marks P₁-P₈, are disposed such that the associatedmarks overlap. Such marks are located so as to correspond to theaforementioned overlap portions of the trapezoidal regions.

Calibration of the optical modules 125 ₁-125 ₇ is illustrated withregard FIG. 4, which also is attached hereto. As shown in FIG. 4,mask-side reference marks M₁-M₈ are projected onto plate-side referencemarks P₁-P₈ via optical modules 125 ₁-125 ₇. Because reference marksM₁-M₈ and P₁-P₈ are formed and disposed to overlap, when the same do notoverlap (e.g., because of device movement or drive anomalies, etc.), theoptical modules are considered to be the cause of such an anomaly andany resultant distortion. Consequently, the relative positions of themarks M₁, M₂ projected by optical module 125 ₁, and the plate-sidereference marks P₁, P₂, are photoelectrically detected by use of asensor 132 (e.g., a TV camera, etc.). In turn, positional displacementdata (dx₁, dy₁) between mark P₁ and the projected image of mark M₁, andpositional displacement data (dx₂, dy₂) between mark P₂ and theprojected image of mark M₂ may be found and derived. With suchdisplacement data (e.g., displacement measurement data, etc.), theparticular adjustment mechanism 126 corresponding to optical module 125₁ may be used to adjust optical module 125 ₁ so that the respectivepositional displacement amounts become zero or tolerable.

Similarly, adjustment is performed relative to optical modules 125 ₂-125₇ such that corresponding mask-side reference marks (M₃-M₈) andplate-side reference marks (P₃-P₈) overlap. Furthermore, the adjustmentof the optical modules 125 ₅, 125 ₆, 125 ₇ may be performed by movingcarriage 112, so that the reference marks enter the exposure fields ofthe optical modules 125 ₅, 125 ₆, 125 ₇. Accordingly, adjustment ispossible so that the seven optical modules are able to project thepattern on mask 113 accurately and within expected tolerances.

Although, prior exposure devices allow calibration of projected imagesand, in particular, calibration of projection optical systems to effectaccurately projected design patterns, such calibration is performed byusing mask-side reference marks disposed on a special mask-sidereference mark plate which may be independent of the mask that is to beimaged and plate-side reference marks disposed on a special plate-sidereference mark plate. Thus, in the case where there is a positioningerror (due to a mask pattern error as shown by the solid lines in FIG.5, for example), the same cannot be corrected by prior exposure devices.That is, because prior exposure devices are centrally concerned withregistration and calibration of reference marks, they do not adequatelyaddress the problems associated with design pattern errors that areoften realized. As such, design patterns like those shown in FIG. 5often have been erroneously projected and imaged onto a plate orsubstrate. And, in particular, the positional errors that can result(especially for large masks) can approach ±1 μm.

Thus, there exists a need to provide new and improved exposure devicesand methods for making and using the same. Such devices must allow masksand reference marks to be integrally formed so that pattern andprojection errors are minimized and avoided, and so that resultantexposures more accurately adhere to design requirements. To be viable,such devices and methods must allow projection exposures on substrateswithout realizing errors often associated with prior exposure devices.

SUMMARY OF THE INVENTION

The present invention has as its principal object to solve theaforementioned problems associated with prior image exposure devices byproviding improved devices that deliver greater exposure accuracy andapparatus efficiency. Such improved devices will, in turn, allowmanufacturers of liquid crystal display (LCD) panels, semiconductorelements, etc. to produce such components more accurately and reliably.

It is another object of the present invention to provide an exposureapparatus for use in a stepper unit that allows accurate imaging to berealized relative to a mask that may contain design pattern errors andthe like.

It is still another object of the present invention to provide anexposure apparatus for use in a stepper unit that accommodates maskshaving integrally formed patterns and reference marks to facilitateaccurate adjustment of corresponding projection optical systems.

It is a further object of the present invention to provide an exposureapparatus for use in a stepper unit that adjusts optical characteristicsof imaging systems by utilizing reference marks that closely relate toattributes of a design pattern formed on a projection mask or reticle.

It is a further object of the present invention to provide an exposureapparatus that may be applied to many different types of stepper unitsincluding mirror-type units without causing significant increases instepper size.

It is another object of the present invention to provide methods formaking and using an exposure apparatus in accordance with the presentinvention.

By providing an exposure apparatus and related methods for making andusing the same, certain benefits are realized. For example, an exposureapparatus according to the present invention will accommodate a mask orreticle that includes a design pattern which is integrally formed withrelated reference marks to be used to calibrate image exposure systemswithin a stepper unit. The present invention will allow masks (orreticles) to be used to reliably produce liquid crystal display (LCD)panels, for example, even when such masks contain design pattern errorsand the like. And, an exposure apparatus according to the presentinvention will more accurately and efficiently respond to errorconditions associated with design pattern errors and the like asautomatic corrections may be made during exposure operations as opposedto realizing defective and unusable finished products. As such, moreaccurate imaging is made possible as reference marks formed on a maskallow an exposure apparatus according to the present invention to moreclosely respond to particularities of design patterns.

The present invention achieves the above-stated objects to deliver theaforementioned benefits by providing an exposure apparatus and methodsfor making and using the same. The exposure device includes at least oneprojection optical system that projects illuminating light, a substratestage which supports a substrate to be exposed by the illuminating lightand which includes a first plurality of reference marks. The exposuredevice also includes a mask stage which supports a mask including a maskpattern to be projected onto the substrate by at least one projectionoptical system. The mask further includes a second plurality ofreference marks intended to correspond to the first plurality ofreference marks. The second plurality of reference marks is integrallyformed with the mask pattern. The projection optical system(s) projectthe illuminating light based on the mask pattern and the secondplurality of reference marks to produce a projected image correspondingto the mask pattern and a plurality of projected images corresponding tothe second plurality of reference marks. The exposure apparatus alsoincludes an adjustment mechanism which adjusts the position of theprojected image on the substrate based on a plurality of positionalrelationships between the plurality of projected images and the firstplurality of reference marks. Also included is a plurality of sensorswhich detect the positional relationships, and a control device whichcontrols the adjustment mechanism based on the positional relationshipsto effect a predetermined plurality of positional relationships betweenthe plurality of projected images and the first plurality of referencemarks.

According to another aspect of the present invention, provided is amethod for making an exposure device. The method includes the steps ofproviding a projection optical system that is configured to projectilluminating light, and providing a substrate stage that is configuredto support a substrate to be exposed by said illuminating light. Thesubstrate stage includes a first reference mark. The method furtherincludes a step of providing a mask stage that is configured to supporta mask including a mask pattern to be projected onto the substrate bythe projection optical system. The mask further includes a secondreference mark. The second reference mark is integrally formed with themask pattern. The method further includes a step of configuring theprojection optical system to project light to produce a projected imagecorresponding to the second reference mark. The projected image is tobecome incident on the substrate stage. The method also includes a stepof providing an adjustment mechanism that is configured to adjust theposition of the projected image on the substrate stage by adjusting theprojection optical system based on a positional relationship between theprojected image and the first reference mark. Finally, the methodincludes the steps of providing a sensor configured to detect thepositional relationship, and providing a control device configured tocontrol the adjustment mechanism based on the positional relationship toeffect a predetermined positional relationship between the projectedimage and the first reference mark.

And, according to another aspect of the present invention, provided is aexposure method for exposing a mask pattern on a substrate via at leastone projection optical system. The method includes the steps ofarranging a first reference mark on a substrate stage that is configuredto support a substrate to be exposed, and arranging a mask on a maskstage. The mask includes a design pattern and an integrally formedsecond reference mark. The method also includes steps of causing thefirst reference mark and the second reference mark to correspond,causing illuminating light to pass through the second reference mark toform a corresponding projected image on the substrate stage, determininga positional relationship between the projected image and the firstreference mark, and adjusting the position of the projected image basedon the positional relationship to effect a predetermined positionalrelationship between the projected image and the first reference mark.Finally, the method includes a step of exposing the substrate based onthe mask pattern.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The present invention is described below with reference to the followingdrawing figures, of which:

FIG. 1 is an oblique diagram of a scanning type exposure deviceaccording to the prior art;

FIG. 2 is a diagram of the optical system modules of the exposure deviceshown in FIG. 1;

FIG. 3 is a diagram of a normal positional relationship betweenmask-side reference marks and corresponding plate-side reference marksrelative to the device shown in FIG. 1;

FIG. 4 is a diagram that illustrates calibration operations relative tothe optical system modules of the device shown in FIG. 1;

FIG. 5 is a diagram that illustrates an imaging problem not adequatelyaddressed and solved by prior art exposure devices like or similar toone depicted in FIG. 1;

FIG. 6 is an oblique diagram of an exposure device according to apreferred embodiment of the present invention;

FIG. 7 is a diagram of the projection optical system modules depicted inFIG. 6;

FIG. 8 is a diagram that illustrates trapezoidal exposure regions andpositional relationships between mask-side reference marks andcorresponding plate-side reference marks;

FIG. 9 is a block diagram of a preferred embodiment of a control systemfor the exposure device depicted in FIG. 6;

FIG. 10A is a diagram of a mask-side reference mark according to apreferred embodiment of the present invention;

FIG. 10B is a diagram of a plate-side reference mark according to apreferred embodiment of the present invention;

FIG. 11A is a diagram of an image retrieved by a first sensor unitwithin the exposure device depicted in FIG. 6;

FIG. 11B is a diagram of an in image retrieved by a second sensor unitwithin the exposure device depicted in FIG. 6;

FIG. 12 is a diagram that illustrates the relative positions ofplate-side/substrate marks used for calibration of the projectionoptical system modules within the exposure device depicted in FIG. 6;and

FIG. 13 is a diagram that illustrates exemplary results realized by anexposure device made in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is now discussed with reference to the drawingfigures that were briefly described above. Unless otherwise specified,like parts are referred to with like reference numerals. A descriptionof the structures included and involved within the present invention isfollowed by a discussion of corresponding operations.

Referring now to FIG. 6, depicted therein is a diagram of an imageexposure apparatus according to a preferred embodiment of the presentinvention. In particular, exposure apparatus 10 is a scanning type ofexposure device that may be used to copy a circuit pattern which hasbeen formed on a mask 13 onto a glass plate or other substrate such asduring a manufacturing process related to production of an LCD displaypanel.

Exposure apparatus 10 is equipped with a base 11 and a moving stage 12which is movable in an X-axis direction (i.e., in a scanning direction).Fixed on moving stage 12 is a carriage 15 (having a U-shapedcross-section). Carriage 15 supports mask 13 and plate 14. Additionally,carriage 15 supports an illumination optical system 17 disposed on abody member 16 which is arranged in the Z-axis direction. A projectionoptical system 18 also is supported by body member 16.

Moving stage 12 is supported on air bearings (not shown) in a floatingarrangement on a pair of guide members 20A and 20B which extend in theX-axis direction. Moreover, a pair of moving magnet type linear motors21 are disposed on both sides of moving stage 12. Moving stage 12 andcarriage 15 are driven along guide members 20A and 20B by linear motors21. Furthermore, linear motors 21 include magnet tracks 21 a that extendin the X-axis direction. Coils 21 b are used to operate linear motors 21and are mounted on moving stage 12.

A plate stage 15A is disposed on carriage 15. Plate stage 15A supports aplate table 23, which further supports plate 14 in a verticalorientation (referred to herein as the XY plane). A mask stage 15B alsois disposed on carriage 15. Mask table 22 supports mask 13 in the XYplane. Mask table 22 may be automatically positioned in the XY plane inaccordance with the present invention through use of motors 24 a-24 cwhich allow adjustment in position and attitude relative to carriage 15.

The surface of plate stage 15A (facing mask stage 15B) is convex.Reference mark plate 28 is fixed to the convex surface of plate stage15A. Moreover, the surface of plate-side reference mark plate 28 is setin practically the same plane as the surface of plate 14. Such stagesurfaces will be understood by those skilled in the art.

In context of the present preferred embodiment, the length of mask 13 inthe X-axis direction (scanning direction) is longer than plate 14.Accordingly, eight mask-side reference marks are integrally formed onmask 13, in the region opposite plate-side reference mark plate 28. Sucheight reference marks are disposed at predetermined spacings in theY-axis direction on mask 13. The use of such integrally formedmask-based reference marks is further discussed below with regard toFIG. 7.

The position of carriage 15 in axial directions X, Y, Z is measured byan interferometric system 30 (FIG. 9) that includes interferometers I1,I2, I3, I4, I5 (e.g., laser interferrometers, etc.).

Projection optical system block 18 is equipped with seven projectionoptical system modules 25 ₁-25 ₇ (projection optical system module 25 ₅is not shown). Projection optical systems 25 ₁-25 ₇ include respectivetrapezoidal exposure fields (FIG. 7) to produce multiple erect imagesthat carefully make up an assembled image. Such projection systems willbe readily apparent to those skilled in the art.

Referring now to FIG. 7, the exemplary projection optical system modules25 ₅-25 ₇, are arranged in an assembly including projection opticalsystem modules 25 ₁-25 ₄. Moreover, the optical axis of the projectionoptical system module 25 ₅ is arranged to lie between the optical axesof projection optical system module 25 ₁ and projection optical systemmodule 25 ₂. The optical axis of projection optical system module 25 ₆is arranged to lie between the optical axes of projection optical systemmodule 25 ₂ and projection optical system module 25 ₃. The optical axisof projection optical system module 25 ₇ is arranged to lie between theoptical axes of projection optical system module 25 ₃ and projectionoptical system module 25 ₄.

Accordingly, projection optical system modules 25 ₁-25 ₇ are arranged ina zigzag state such that the trapezoidal projection regions PA₁-PA₄ ofprojection optical system modules 25 ₁-25 ₄ and the trapezoidalprojection regions PA₅-PA₇ of projection optical system modules 25 ₅-25₇ (FIG. 3), overlap (at end portions thereof) by predetermined amountsin a Y-axis direction (i.e., a non-scanning direction). As such,exposures become possible by means of scanning mask 13 and plate 14 withrespect to the projection optical system block 18. Accordingly, if mask13 and plate 14 are scanned in a X-axis direction by driving stage 12 tomove an entire pattern contained on mask 13 can be copied/projected ontoplate 14 (e.g., in one or more scans). As such, in the present preferredembodiment, linear motors 21, moving stage 12, and carriage 15, causesubstrate stage 15A and mask stage 15B to move simultaneously in thescanning direction.

In the present preferred embodiment, projection optical system modules25 ₁-25 ₇, and, in particular, optical characteristics thereof, areadjusted by adjusting mechanisms 26. As such, adjusting mechanisms 26functions to adjust the position of projected images (copy images) ontoplate 14. Accordingly, it is possible to adjust the positionaldisplacement (shift), image rotation, magnification, etc. as opticalcharacteristics associated with each projection optical system 25. Forexample, adjustment mechanisms 26 can adjust an image shift amount bycausing a plane parallel to the interior (not shown) of a projectionoptical system module to rotate around respective X and Y axes.Additionally, adjustment mechanisms 26 can adjust magnification bydriving one or more lenses within a projection optical system modulealong a respective optical axis. Also, adjustment mechanisms 26 can beconfigured to adjust rotation of images, etc. by rotating one or moreprisms within the interior of a projection optical system module. Suchadjustments to affect optical characteristics, for example, ofprojection optical system modules within the present invention arediscussed below with regard to FIG. 8. Such adjustments may beaccomplished by an adjustment mechanism similar or like a mechanismshown and described in U.S. Pat. No. 5,729,331. The material disclosedin U.S. Pat. No. 5,729,331 is incorporated herein by reference.

On reference mark plate 28 as shown in FIG. 8, for example, plate-sidereference marks P₂-P₇ are disposed in positions corresponding to theoverlap portions of mutually adjacent trapezoidal projection regions.Moreover, plate-side reference marks P₁, P₈ are disposed in positionswhich correspond to the inclined portions of trapezoidal projectionregions PA₁ and PA₄.

In terms of mask 13, mask-side reference marks M₁-M₈ are integrallyformed therewith and are intended to correspond to plate-side referencemarks P₁-P₈. In the present preferred embodiment, mask-side referencemarks M₁-M₈, are drawn/formed on mask 13 at the same time that designpattern DP is formed by a pattern generator such as one incorporating anelectron beam exposure device, etc. In the event that drawing errors arerealized during the mask generation process (such as those resultingfrom a device drive errors, etc.), errors, like those indicated byE_(x), E_(y), may and often result. The production of masks and reticleswill be immediately understood by those skilled in the art.

As such, in the present preferred embodiment, sensors 32 ₁-32 ₈ (e.g.,TV video cameras, CCD devices, etc.) (FIG. 7) are included tophotoelectrically detect the positions of plate-side reference marksP₁-P₈ relative to images of mask-side reference marks M₁-M₈ which areprojected onto plate-side reference mark plate 28. The projection ofmask-side reference mark images results from the projection ofilluminating light by optical system modules 25 ₁-25 ₇. Such sensorsproduce signals that correspond to data values that can be used toderive positional displacement and related distance measurementinformation. Sensors 32 ₁-32 ₈ are disposed at the back of referencemark plate 28 (as shown in FIG. 7). Moreover, sensors 32 ₁-32 ₈ may bedisposed and supported within carriage 15.

The structures discussed above are coupled together in the exposuredevice of FIG. 6 and may be operated and controlled automaticallythrough use of a processing unit like or similar to central processingunit. An exemplary arrangement is illustrated in FIG. 9.

Referring now to FIG. 9, depicted therein is a block diagram of acontrol system that may be incorporated into exposure device 10 tocontrol the same to correct for design pattern anomalies, etc. Inparticular, a main control device 36 (e.g., a microcomputer,minicomputer, etc.) is coupled to an interferometer system 30, analignment sensor unit 34, a sensor group 32, motors 24, linear motors21, and a control mechanism 26.

Interferometer system 30 includes interferometers I1, I2, I3, I4, I5(e.g., laser interferometers, etc.) as shown in FIG. 6. Interferometersystem 30 produces movement data in relation to two axial directions(e.g., X and Y directions) based on the movement of carriage 15, masktable 22, and plate table 23. Such movement data is detected byinterferometers I1-I5 and, in turn, is provided to main control device36 for appropriate processing as described below in regard to FIGS. 10A,10B, 11A and 11B below.

Alignment sensor unit 34 includes a pair of alignment sensors such asimaging devices, (video cameras such as TV cameras, microscopes, etc.,)which are equipped with indexes set to desired detection standards. Suchalignment sensors (.e.g., microscopes, etc.) may include sensorsselected among sensors 32 ₁-32 ₈. Accordingly, when carriage 12 is in aloading position (as shown in FIG. 6), a pair of reference marks for usein mask alignment (not shown) may be disposed on plate-side referencemark plate 28. A pair of reference marks P₁-P₈ may be used for suchpurposes. In any case, the pair of reference marks used for maskalignment are positioned (through carriage positioning, for example) sothat the aforementioned indexes of the alignment imaging sensors (e.g.,microscopes, etc.) correspond thereto. The position of the index of analignment imaging device (e.g., registration marks of a microscope,etc.) relative to a respective alignment mark (not shown in the drawing)may be measured and calculated in accordance with the pixel pitch of thealignment imaging device (e.g., pixel pitch of a TV type camera, etc.)at particular magnifications, etc. When measurement values are obtainedor otherwise derived, they are provided to main control device 36 forfurther processing.

Motors 24 include, for example, motors 24 a-24 c as shown in FIG. 6.Linear motors 21 include a pair of linear motors as shown in FIG. 6.Adjustment mechanism 26 includes adjustment mechanisms 26 ₁-26 ₇.

It will be readily understood that the structures illustrated in FIGS.6-9 are intended to be assembled and operatively arranged as indicatedin FIG. 9. Accordingly, once the structures illustrated in FIGS. 6-9 areprovided during an assembly and manufacturing process (e.g., a manualand automated assembly process), for example, a stepper unit includingan exposure apparatus according to the present invention may beproduced. That is, the present invention contemplates the manufacture ofa stepper unit and/or particular exposure apparatus in which accurateimaging is realized through use of masks including integrally formeddesign patterns and mask reference marks. Because an exposure apparatusaccording to the present invention will accommodate a mask having adesign pattern and reference marks formed proximately close thereto(e.g., reference marks that are formed on a mask in close relation to adesign pattern), an accurate exposure of the mask will be possible evenin the case that such a mask contains design pattern errors.

In operation, the structures shown in FIGS. 6-9 are used and calibratedto effectively expose images through mask 13 onto plate 14. Suchoperation is next described.

Motors 24 a-24 c are controlled by main control device 36 based onmeasurement values sensed or otherwise derived in accordance with theoperation of alignment sensor unit 34. After motors 24 a-24 c are causedto operate, mask 13 will be aligned within mask stage 158 so thatmask-side reference marks M₁-M₈ correspond to plate-side reference marksP₁-P₈. Correspondence of reference masks implies that mask-sidereference marks M₁-M₈, for example, are in position to causecorresponding images thereof to be projected onto reference mark plate28. Such correspondence may also cause one ore more mask-side referencemarks to align with corresponding plate-side reference marks.

Measurement values (data) from interferometer system 30 are obtained andinput to main control device 36. Such data will be used by main controldevice 36 to control a pair of linear motors 21 to cause carriage 15 tomove until projection optical system modules 25 ₁-25 ₄ are in a positionopposite to plate-side reference mark plate 28. Such a state is shown inFIG. 7. In such a state, a shutter (not shown in the drawing) may beopened thereby allowing illuminating light from illuminating lightsource 17 to pass. Accordingly, when the four trapezoidal projectionregions corresponding to the projection regions of the projectionoptical system modules 25 ₁-25 ₄ are illuminated by illuminating lightfrom illumination light source 17, main control device 36 uses sensors32 ₁-32 ₈ to measure or otherwise detect the relative positionalrelationships of the projected images of mask-side reference marks M₁-M₈that are projected onto or near the plate-side reference marks P₁-P₈ onreference mark plate 28.

Accordingly, to calculate such positional relationships, main controldevice 36 may be programmed via computer software, etc. In particular,to obtain mathematical representations of the positional relationships,appropriate calculations are performed. To illustrate such calculations,the following discussion is directed to exemplary projection opticalsystem module 25 ₁, but may be based on measurements related to anyother projection optical system modules within exposure device 10.

To illustrate such calculations, a exemplary mask-side reference mark Mis formed as a double-cross shaped mark as shown in FIG. 10A. Acorresponding exemplary plate-side reference mark P is formed as across-hair shaped mark as shown in FIG. 10B. Images formed by areference mark like mark M in two instances (identified as referencemark M₁ in FIG. 11A and as reference mark M₂ in FIG. 11B) areillustrated in FIGS. 11A and 11B, respectively. Accordingly, in FIGS.11A and 11B, plate-side reference marks P₁ and P₂ correspond toreference marks M₁ and M₂, respectively.

When projected images of reference marks M₁ and M₂ as shown in FIGS. 11Aand 11B are detected by sensors 32 ₁, 32 ₂, for example, relativeposition data (measurement values, etc.) may be derived. As such, withthe center point of the plate-side reference marks P₁, P₂, set asorigins, for example, appropriate measurement values may be derived asvalue pairs (dx₁, dy₁) and (dx₂, dy₂). The letter “d” is intended toindicate a distance value relative to a particular axis (e.g., “dx₁”indicates a distance value along an X-axis from a particular originpoint). Such values may then be provided to main control device 36.Based on such measurement values, correction values for the projectedimages for projection optical system module 25 ₁ may be calculated bymain control unit 36 in accordance with the following equations (1)-(4):

Correction value of shift amount in an X direction=−(dx ₁ +dx ₂)/2  (1)

Correction value for shift amount in a Y direction=−(dy ₁ +dy ₂)/2  (2)

Correction value for magnification=−(dy ₂ −dy ₁)/L  (3)

Correction value for rotation=−(dx ₁ −dx ₂)/L  (4)

The negative sign (−) on the right-hand side of each equation (1)-(4) isapplied because such results are correction values (intended to indicatecorrective movement back to a registered or correct position). Inequations (3) and (4), L is the distance between the measurement points(e.g., the distance between center points of reference marks P₁ and P₂)(as shown in FIG. 7).

Similarly, relative position data (dx₃, dy₃), (dx₄, dy₄) correspondingto mask-side reference marks M₃, M₄ relative to plate-side referencemarks P₃, P₄ may be obtained via sensors 32 ₃, 32 ₄. Accordingly, thecorrection values of the projected images for projection optical systemmodule 25 ₂ may be calculated by main control device 36 based onequations (1)-(4).

Similarly, relative position data (dx₅, dy₅), (dx₆, dy₆) for mask-sidereference marks M₅, M₆ relative to plate-side reference marks P₅, P₆ maybe obtained via sensors 32 ₅, 32 ₆. Accordingly, the correction valuesof the projected images (copy images) for projection optical systemmodule 25 ₃ may be calculated by main control device 36 based onequations (1)-(4).

Additionally, relative position data (dx₇, dy₈), (dx₇, dy₈) formask-side reference marks M₇, M₈ relative to plate-side reference marksP₇, P₈ may be obtained via sensors 32 ₇, 32 ₈. Accordingly, thecorrection values of the projected images (copy images) for projectionoptical system module 25 ₄ may calculated by main control device 36based on equations (1)-(4).

Accordingly, after calibration is achieved relative to projectionoptical systems 25 ₁-25 ₄, as described above, additional, similarcalibration techniques may be carried out to calibrate projectionoptical systems 25 ₅-25 ₇. For example, after deriving the measurementvalues of interferometer system 30, main control device 36 may controllinear motors 21 to causes carriage 15 to move in the X-axis direction(FIG. 6) until projection optical system modules 25 ₅-25 ₇ reach aposition opposite plate-side reference mark plate 28. After suchmovement, a shutter (not shown) may be closed. Accordingly, projectionoptical system modules 25 ₅-25 ₇ will be positioned opposite mask-sidereference marks M₂-M₇. In this state, the shutter (not shown in thedrawing) may be re-opened a predetermined amount to illuminaterespective trapezoidal projection regions corresponding to projectionoptical system modules 25 ₅-25 ₇. Accordingly, the projected images ofthe mask-side reference marks M₂, M₃, M₄, M₅, M₆, M₇ will be projectedonto plate-side reference marks P₂, P₃, P₄, P₅, P₆, P₇ by projectionoptical system modules 25 ₅-25 ₇. Thereafter, main control device 36measures the relative position of the plate-side reference marks P₂, P₃,P₄, P₅, P₆, P₇ which correspond to the projected images of the mask-sidereference marks by using outputs of sensors 32 ₂, 32 ₃, 32 ₄, 32 ₅, 32₆, 32 ₇, respectively. Based on such measurement values output bysensors 32 ₂, 32 ₃, 32 ₄, 32 ₅, 32 ₆, 32 ₇, main control device 36determines the correction values (shift, magnification, rotation, etc.)for the projected images of the projection optical system modules 25₅-25 ₇ in accordance with equations (1)-(4) as described above.

After main control device 36 determines the aforementioned appropriatecorrection values, main control device 36 adjusts the imagingcharacteristics of the projection optical system modules 25 ₁-25 ₇ viaadjustment mechanisms 26 respectively disposed therefore. Accordingly,the imaging characteristics of the projection optical system modules 25₁-25 ₇ are calibrated such that the eight reference marks M₁-M₈ formedon mask 13 are projected accurately onto plate-side reference marksP₁-P₈ and regardless of design pattern errors that exist on mask 13. Asa result of such calibration, distortions of the projection opticalsystem modules 25 ₁-25 ₇ and/or drawing errors associated with thepattern on mask 13 may be corrected.

After calibration processes are performed as described above and aftercarriage 15 is caused to move to effect scanning at a predeterminedspeed along the X-axis illustrated in FIG. 6, for example, the patternon mask 13 is copied/projected onto plate 14 by projection opticalsystem modules 25 ₁-25 ₇. Accordingly, the design pattern exposed onplate 14 is as shown by the solid line in FIG. 12. Drawing errors andthe like in mask 13 have little to no effect on the imaging process andare minimized, if not totally negated, as illustrated by the dofted linein FIG. 13.

In the case of the above-described preferred embodiment of the presentinvention, projection optical system 18 includes seven projectionoptical system modules 25 ₁-25 ₇ and a related number of referencemarks. The present invention, however, is not so limited. To thecontrary, any number of projection optical modules may be included andused. Additionally, any number of reference marks may utilized to suitparticular design and calibration requirements.

Also, exemplary preferred embodiments of the present invention have beenapplied to a scanning type of exposure device in which the mask andplate (substrate) move as they are integrally supported by a carriageassembly. The present invention, of course, is not so limited. To thecontrary, the present invention may be applied, to an exposure device ofthe type that include scanning projection optical systems, and to thosethat utilize static (non-moving) exposure projection systems.

Thus, having fully described the present invention by way of examplewith reference to the attached drawing figures, it will be readilyappreciated that many changes and modifications may be made to theinvention and to the embodiments shown and/or described herein withoutdeparting from the spirit or scope of the present invention which isdefined in and covered by the appended claims.

What is claimed is:
 1. An exposure apparatus which exposes a pattern ofa mask onto a substrate, said apparatus comprising: a plurality ofprojection optical systems disposed between said mask and said substrateto project said pattern onto said substrate; a substrate stage whichsupports said substrate, said substrate stage including a firstplurality of reference marks; a mask stage which supports said maskincluding a second plurality of reference marks which is integrallyformed with said mask pattern, said mask stage positioning said masksuch that images of said second plurality reference marks projected byat least one of said projection optical systems correspond to said firstplurality reference marks; a plurality of sensors which detect apositional relationship between said images of said second pluralityreference marks and said first plurality reference marks; and anadjustment system connected to said plurality of sensors to adjust atleast one of said plurality of projection optical systems in accordancewith said positional relationships, said adjustment system adjusting animaging error including an error of said mask and an error of at leastone of said projection optical system.
 2. The exposure device accordingto claim 1, wherein said second plurality of reference marks is arrangedto correspond to said mask pattern.
 3. The exposure apparatus accordingto claim 1, wherein said adjustment system further comprises a pluralityof motors which move said mask based on said predetermined plurality ofpositional relationships.
 4. The exposure apparatus according to claim1, wherein said adjustment system further comprises a plurality ofmotors which move said mask stage together based on said predeterminedplurality of positional relationships.
 5. The exposure apparatusaccording to claim 1, wherein said adjustment system further includes atleast one adjustment device corresponding to said at least oneprojection optical system, said at least adjustment device adjusting theposition of a particular one of said plurality of projected images byadjusting said corresponding at least one projection optical system. 6.The exposure apparatus according to claim 1, wherein said plurality ofsensors includes a pair of alignment microscopes, each alignmentmicroscope including an alignment reference mark, each alignmentmicroscope determining an alignment positional relationship between acorresponding alignment reference mark and a corresponding firstreference mark from said plurality of reference marks, said adjustmentsystem adjusting said at least one projection optical system based onsaid aligmnent positional relationship.
 7. The exposure device accordingto claim 1, wherein said mask stage and said substrate stage arearranged to move in a predetermined direction to facilitate scanning ofsaid mask to expose said substrate.
 8. The exposure apparatus accordingto claim 1, wherein said projection optical systems include at least twoprojection optical units arranged at a predetermined spacing along ascanning direction, and such that a first projection regioncorresponding to a first projection optical unit and a second projectionregion corresponding to a second projection optical unit partiallyoverlap in a direction orthogonal to said scanning direction, saidplurality of sensors being arranged at predetermined spacing in saiddirection orthogonal to said scanning direction.
 9. The exposureapparatus according to claim 6, wherein said second reference mark isarranged to correspond to said mask pattern.
 10. The exposure apparatusaccording to claim 6, wherein said mask stage and said substrate stageare arranged to move together in a predetermined direction to facilitatescanning of said mask to expose said substrate.
 11. An exposureapparatus which exposes a pattern of a mask onto a substrate, saidapparatus comprising: a plurality of projection optical systems disposedbetween said mask and said substrate to project said pattern onto saidsubstrate; a substrate which supports said substrate and which includesa first reference marks; a mask stage which supports said mask includinga second reference mark which is integrally formed said pattern, saidmask stage positioning said mask such that an image of said secondreference mark projected by at least one of said projection opticalsystems corresponds to said first reference mark; a sensor which detectsa positional relationship between said image of said second referencemark and said first reference mark; and an adjustment system connectedto said sensor to adjust at least one of said projection optical systemsin accordance with said positional relationship, said adjustment systemadjusting an imaging error including an error of said mask and an errorof at least one of said projection optical system.
 12. The exposureapparatus according to claim 11, wherein said adjustment system furthercomprises a plurality of motors which move said mask based on saidpositional relationship.
 13. The exposure apparatus according to claim11, wherein said projection optical systems project the pattern onto thesubstrate such that portions of the pattern overlap each other.
 14. Theexposure apparatus according to claim 11, wherein a projection area ofsaid projection optical systems has a rectangular shape.
 15. An exposureapparatus, comprising: at least one projection optical system whichprojects illuminating light; a substrate stage which supports asubstrate to be exposed by said illuminating light, said substrate stageincluding a first plurality of reference marks; a mask stage whichsupports a mask including a mask pattern to be projected onto saidsubstrate by said at least one projection optical system, said maskfurther including a second plurality of reference marks corresponding tosaid first plurality of reference marks, said second plurality ofreference marks is arranged in relation to said mask pattern; said atleast one projection optical system projecting said illuminating lightbased on said mask pattern and said second plurality of reference marksto produce a projected image corresponding to said mask pattern and aplurality of projected images corresponding to said second plurality ofreference marks; an adjustment mechanism which adjusts a position ofsaid projected image on said substrate based on a plurality ofpositional relationships between said plurality of projected images andsaid first plurality of reference marks, said adjustment mechanismfurther including a plurality of motors which move said mask based onsaid predetermined plurality of positional relationships and which movesaid substrate stage and said mask stage together based on saidpredetermined plurality of positional relationships, and at least oneadjustment device corresponding to said at least one projection opticalsystem, said at least one adjustment device adjusting the position of aparticular one of said plurality of projected images by adjusting saidcorresponding at least one projection optical system; a plurality ofsensors which detect said positional relationships, said plurality ofsensors includes a pair of alignment microscopes, each alignmentmicroscope including an alignment reference mark, each alignmentmicroscope determining an alignment positional relationship between acorresponding alignment reference mark and a corresponding firstreference mark from said plurality of reference marks, said adjustmentmechanism adjusting said at least one projection optical system based onsaid alignment positional relationship; and a controller which controlssaid adjustment mechanism based on said positional relationships toeffect a predetermined plurality of positional relationships betweensaid plurality of projected images and said first plurality of referencemarks.
 16. An exposure apparatus which exposes a pattern of a mask ontoa substrate while said mask and said substrate move in a scanningdirection, the apparatus comprising: a projection optical systemdisposed between said mask and said substrate to project said patternonto said substrate; a substrate stage which supports and substrate andwhich includes a first reference mark; a mask stage which supports saidmask including a second reference marks, which are arranged in adirection orthogonal to said scanning direction with a predeterminedinterval, said mask stage positioning said mask such that at least oneof image of said second reference marks projected by said projectionoptical system corresponds to said first reference mark; a sensor whichdetects a positional relationship between said at least one image ofsaid second reference marks and said first reference mark; and anadjustment system connected to said sensor to adjust said projectionoptical system in accordance with said positional relationship, andadjustment system adjusting an image error including an error of saidmask and an error of said projection optical system.
 17. The exposureapparatus according to claim 16, wherein a magnification of saidprojection optical system is substantially equal to one.
 18. Theexposure apparatus according to claim 16, wherein a projection area ofsaid projection optical system has a rectangular shape.
 19. The exposureapparatus according to claim 16, wherein said substrate stage is drivenby a linear motor.
 20. The exposure apparatus according to claim 16,wherein said adjustment system comprises an optical member.
 21. Theexposure apparatus according to claim 20, wherein said optical member isa prism.
 22. The exposure apparatus according to claim 16, wherein saidsensor is mounted on said substrate stage.